We Are A Constant
by Spydurwebb
Summary: In the Trividian Universe...Things are quiet in the attic when Sarah Jane receives a visit from someone she never thought she'd see again.
1. Chapter 1

**_A/N: This takes place in the same world as my story Trividian Conundrum. Without having to read all of that, the short version and what is pertinent to this is that after the Doctor dropped Sarah off in Aberdeen, she had a brief relationship with Harry Sullivan, Susan being the product of that relationship. Susan and Sarah had a rocky relationship for years, but settled into a friendly mother/daughter relationship as Susan became an adult. This story is set after Series 3 of SJA. Of course all the regular characters belong to the BBC, they just feed my imagination._**

WE ARE A CONSTANT

Sarah sat at her computer in the attic, typing away on an article. After a few moments, she took off her glasses and pinched the bridge of her nose between her thumb and finger. It had been a quiet few weeks on the alien chasing front, so it gave her opportunity to get in a few freelance articles. Glancing down at her watch, she knew it was just about time for Luke to be getting home from school.

Saving her document, she turned to Mr. Smith. 'Any unusual activity, Mr. Smith?'

'No, Sarah Jane, everything is still very quiet.'

'It's nice to have some peace and quiet for a while. Let me know if you detect anything.'

As she started to leave, Mr. Smith called back out to her. 'Sarah Jane, so much for peace and quiet. I am detecting a temporal disturbance.'

Sarah quickly went to stand in front of her supercomputer. 'Where?'

'It's unstable. The first flux occurrence was approximately a half-mile away. Now it seems to be concentrated even closer.'

'Pinpoint the location as best as possible.'

After a quick moment, Mr. Smith continued. 'The occurrence is now centred right here in the attic, directly behind you.'

Sarah turned around quickly, just in time to see the TARDIS materialise. She smiled, expecting to see the young Doctor wearing the pinstriped suit and trainers emerge. Instead, the door opened, and a head emerged and looked around.

'Ah, Sarah, there you are! Perfect landing, although, the old girl had a bit of trouble homing in on you. You've moved.' He stepped out of the TARDIS and looked around, pushing his hat to the back of his head full of wild, brown curls, obviously impressed at his surroundings. 'This is very nice, Sarah, I must say.'

Sarah just stood there, eyes wide. Each time she tried to talk, no words would come out.

'C'mon Sarah, not even a "Hello" for your best friend?' He smiled, the large smile of the Cheshire cat, bright blue eyes bulging just as Sarah remembered.

She finally jolted herself into speaking. 'Doctor, it's YOU!' She looked around slowly, feeling rather lightheaded.

'Where are we, Sarah? This isn't Croydon.'

'No, we're in Ealing. I've not lived in Croydon for years. Doctor, I am surprised to see you. Or should I say, this version of you.'

The attic door opened and Luke rushed in. 'Hey Mum, I just put the kettle on.' He noticed the TARDIS instantly. Walking around the TARDIS, he recognized the tall man from some of Sarah's old pictures. 'Doctor?' he questioned.

The Doctor smiled. 'Seems you have me at a slight disadvantage, young man.'

Sarah walked over and put an arm around Luke's shoulders. 'Luke, yes, this is the Doctor, the one I did the majority of travelling with. Doctor, this is my son, Luke.'

The Doctor shook Luke's hand enthusiastically, but stared deeply into Sarah's eyes. 'Sarah, what year is this?' he asked, his velvet tones lower than she'd heard them in a long time.

'2010. February 25th.'

Looking back at Luke, he asked, 'How old are you, Luke?'

Sarah reached out and put a hand on the Doctor's arm, 'Can I talk to you for a moment?' She guided him away from Luke to another portion of the attic. 'I know what you're thinking. In my past, your future, we'll have that conversation, so I'm not having it with you now. I adopted Luke three years ago.'

The door to the attic swung open again. Susan ran in, out of breath. She pointed at the TARDIS and smiled. 'I knew it.' Then she saw the Doctor and frowned. 'Ah. Oh dear.' She pointed back towards the door. 'Bad timing, I should be going.'

As she turned to leave, Sarah called out to her in a tone she shouldn't ignore. 'Susan.' Susan turned on her heels back to face Sarah and the Doctor. Sarah just raised her eyebrows and gave her a questioning look.

'I saw the TARDIS, like it was going to materialise in front of me, but then it disappeared. Then I heard it again in the distance and figured this was the only place nearby that the Doctor would go.'

The Doctor stalked over to her. 'You're what I picked up on. How did you hear the TARDIS? You were over half a mile away from here when I landed.'

Susan pointed at her ear and grinned. 'Super hearing. Picked it up from living two years on an alien planet.'

'Timelines, Sue,' Sarah warned.

Glaring down at her, the Doctor frowned, but Susan just stood there, smiling. After a few moments, the Doctor finally spoke. 'Are you still a soldier?'

'I don't know how to be anything different.'

Sarah frowned at Susan's statement, but still said nothing as she tried to gauge the situation.

'What are you doing here?' the Doctor challenged.

'I'm not going to tell you that.'

'You are the most infuriatingly stubborn human I have ever met!' he yelled. 'And after all this time, I still don't know your name to properly yell at you.'

That's when Sarah decided to intervene. 'Excuse me, but would one of you two like to tell me what's going on?'

'I had a bit of a disagreement with one of the Colonels in UNIT and this young woman managed to stonewall me at every attempt to gather information.'

Susan rolled her eyes. 'Oi, it isn't like I knew who you were at the time. And you were after classified information. You are one of the most annoyingly condescending aliens I've ever met. And believe me, I've met several.' She finally turned to Sarah. 'When he was like this, how did you manage to travel with him as long as you did?'

The Doctor turned back to Sarah. 'Sarah, how do you know this unpleasant young woman?'

Susan looked at Sarah and saw the look in her eyes and frowned before looking back at the Doctor. She extended her hand out to the Doctor. 'Doctor, perhaps we should start over. I'm Susan. Susan Sullivan.'

Taking Susan's hand and shaking it slowly, he stared at her. 'Sullivan? Are you related to Harry Sullivan?'

Susan finally smiled. 'He's my father.'

'Well, that explains it. Harry always was an imbecile. Looks like he passed it on.' Susan shot a thought towards the Doctor, with a glare in her eyes to match. It obviously took the Doctor by surprise, as he visibility jerked his head towards her. A slow smile crossed his features. 'Oh that's very good. I take it all back, Susan,' he said as he reached out and shook her hand warmly.

Sarah stepped up. 'OK, now that the introductions are over. Luke said he'd put the kettle on. Sue, why don't you and Luke go downstairs and get the tea. The Doctor and I will be down in a minute.'

Susan nodded. 'Right Mum, c'mon Luke.'

As soon as Susan and Luke had closed the door of the attic behind them as they left, the Doctor turned back to Sarah. 'Susan just called you "Mum".'

Sarah ignored his statement and walked over and put a hand on his arm, partially just to reassure herself that he was there. 'Doctor, why are you here? I mean, this version of you. It's been over thirty years. How long has it been for you?'

The Doctor stared back at Sarah, his own blue eyes piercing into hers. 'Thirty years? I missed by thirty years?' He reached out and put his hand on her cheek, then stepped back, took off his hat and ran a hand through his curls. 'How could I have missed by that much?' He began to walk around the room and mutter to himself about his calculations and whether or not the TARDIS herself was to blame.

Sarah watched him for a minute. 'Were you trying to get back to where you dropped me off?' she asked softly.

'What? You didn't think I'd just leave you did I?' He almost sounded angry.

She frowned, staring only at the floor. 'I didn't at first.' She paused before continuing, glancing up and seeing him staring at her, she couldn't stop the tears beginning to well up. She'd already taken out her anger at her perceived abandonment on the more recent regeneration she'd met at Deffry Vale. Even though this regeneration in front of her now was the one that left her, she found that she no longer harboured any anger, only sadness at what could have been. 'I kept my ears perked up, listening for the TARDIS, jumping at shadows. But then, later, as time passed, I wasn't sure if I'd done something wrong, or if you'd died. The uncertainty tore me up inside for a long time.'

'Oh, Sarah,' his rich tones finally too much for her to bear and the tears began to flow freely. As he saw her tears, he quickly closed the distance between them and wrapped his arms around her. 'I never meant for this to happen, you have to believe me.'

Sarah pulled back slightly, but kept a tight hold on the Doctor's scarf. 'Oh, I know, but still.' She reached up and wiped away the tears. 'I promised myself that I wouldn't do this.'

'I couldn't come back right away, you understand.'

'Timelines, I know. Maintaining your history, you'll tell me a little about it someday.'

The Doctor frowned and stepped back away from her. 'So you've seen me?'

'Not this version of you, but yes, multiple times.'

He grinned. 'That's good, that's very good.' When she didn't share his smile, he continued, 'Isn't it?' He reached out and put a hand on each of her shoulders. 'I don't want details, Sarah, but I've kept my promise, haven't I? We are still a constant?' he asked.

Sarah gave a slight shrug. 'I guess that depends on what you mean by a constant.'

'You seem to have a good life here, Sarah.'

Smiling, Sarah nodded. 'It's not been typical, but then I probably would've been bored with that.' She nodded her head towards the attic door. 'Why don't you come downstairs for a minute and have a cup of tea? You'll love Luke, he saved the world the day he was born.'

Intrigued, he raised his eyebrows. 'Is he human?'

'Completely human, but grown by aliens during an invasion attempt.'

'And Susan the soldier?' He looked at Sarah and frowned. 'Harry Sullivan's child?'

Sarah sighed. 'Harry was very kind to me after you left, and we've remained very good friends over the years. Susan didn't know I was her mother until she was sixteen.'

Smiling, the Doctor draped an arm over Sarah's shoulder and steered her towards the attic door. 'Now that sounds like a story, my Sarah.'

Sarah laughed. 'It is, but it's one I can't tell you.' She relished the moment with "her" Doctor, knowing it couldn't last, no matter how much she wanted it to.

~!~!~!~


	2. Chapter 2

**_A/N: OK, so I thought this was originally going to be a one-shot, but it apparently needed to be a two-shot! Of course all the regular characters belong to the BBC, they just feed my imagination._**

WE ARE A CONSTANT - PART TWO

Susan finished making the tea and looked at Sarah and the Doctor sitting at the table. They were looking at each other, but not saying anything. Sue looked over at Luke and motioned for him to come stand close to her. 'Why don't you call Clyde and see if he can meet you at the park or something?' she whispered to him.

He gave her a questioning glance and whispered, 'Why?'

'Because Mum and the Doctor need some time alone.'

'What about you?'

'Don't worry, I'm going to get out of here too.' She took over two cups of tea and sat one each in front of the Doctor and Sarah. 'Here you go,' she said aloud. 'You two are killing me with the silence and staring into each other's eyes, and I happen to know that you're not communicating, because I'm not picking it up, and I would.'

Sarah glanced up at her, 'Sorry Susan. This just all seems so surreal.'

Susan reached up and squeezed Sarah's shoulder. 'I understand, Mum.' She motioned for Luke to head out of the room. 'Luke is going to go meet up with Clyde, and I'm going to disappear for a bit.'

The Doctor looked from Susan to Luke as he left, but said nothing. Sarah looked up at Susan, then stood up to whisper quickly in her ear.

Susan nodded, 'Don't worry, I'll take care of it.'

Sarah reached up and cupped Susan's cheek with her hand. 'Are you all right?'

'Of course,' Susan said, smiling. 'This is what we do, right?' At that, she gave the Doctor a quick glance and headed out the room.

The Doctor and Sarah both watched as Susan left the room. 'Your children remind me of you, Sarah Jane.'

Sarah laughed as she sat back down. 'They're both amazing. Luke is learning everything so fast and is amazingly brilliant, despite his age. It causes him some awkward moments, but his friends help a lot. I've had some rocky times with Susan, just because of everything she's gone through, but I wouldn't trade any of that for the closeness we have now because of it.'

The Doctor reached out and took Sarah's hand in his. 'I've missed you, Sarah.'

Sarah looked down at their hands, 'Why are you really here, Doctor?'

'Can't I just come to see my best friend?'

'Thirty years after the fact? That doesn't sound like you at all.'

'Well, I really shouldn't be here.'

Sarah shook her head. 'You know you're crossing your own timeline and that's never a good thing.'

The Doctor stood up. 'You're right, this does bend more than a few laws.' As Sarah stood up, he wrapped her in a warm embrace, 'But it's worth every second. I'm sorry I couldn't come back for you, Sarah.'

She buried her head in his scarf, committing each sensation to memory. 'I understand. I don't have to like it, but I think I finally understand.'

He pulled back, 'I know I'll see you again, and I'm looking forward to that, but I don't know if you'll see me.'

'Sad thing is, I understand exactly what you mean.' She looked up at smiled at him. 'Take care of yourself, Doctor.'

'And you, my Sarah Jane.' He leaned over and kissed Sarah's forehead before quickly walking out of the kitchen and back up towards the attic and the TARDIS.

Sarah leaned against the table and sighed deeply before reaching up and wiping away a stray tear.

~!~!~!~

As Luke left to go meet Clyde, Susan walked into the attic, giving her mother and the Doctor some time alone. Susan thought long and hard about what she was going to need to do. She could sense the timelines getting out of whack even as the minutes progressed. She walked over to the TARDIS and affectionately patted the door. 'You know, old girl, don't you?' She smiled as she felt the familiar pulse from the TARDIS echo through her mind.

She heard the Doctor's footfalls coming up the landing, so she leaned against the TARDIS casually and folded her arms as the Doctor entered.

'Ah, Susan the soldier, what are you doing here?'

'We need to talk, Doctor.'

'About?'

She nodded back towards the TARDIS. 'In the TARDIS, away from any ears.'

The Doctor shook his head, 'I don't think so, here is fine.' Susan sighed and took out her own key, unlocked and quickly entered the TARDIS. The Doctor quickly followed her, an angry glare darkening his features. 'How did you get a key to my TARDIS?' he demanded.

'You gave it to me. Part of the privilege of travelling with you. Not to mention the other reason, the main reason really.'

'What reason?'

Susan walked up to him and stared directly at him. 'These eyes look familiar?'

'What?'

'They're yours. Mum doesn't have blue eyes.'

'Harry does.'

Susan raised an eyebrow to look at him. 'Yes, he does, but he can't tell you this.' She shot a thought in his direction.

The Doctor took in her expression, posture and attitude. She shot a second thought in his direction causing him to take a physical step back. 'I did nothing of the sort!' he exclaimed defensively.

'C'mon Doctor. You abandoned Sarah knowing full well she was pregnant,' Susan's tone wasn't one of anger, just stating the fact.

The Doctor dropped his head for a moment before looking back up at Susan, his voice taking a defeated tone, knowing she was at least partially right. 'I suspected, although I never knew for sure. I saw things in the Matrix on Gallifrey. I couldn't come back right away, but I needed to see her.' He walked up to Susan and put a tentative hand on her arm. 'And I needed to see if I was right.'

Susan smiled gently. 'You were, and here I am.'

The Doctor reached out and used his index finger under Susan's chin to turn her face up towards his, looking into her eyes, studying all her features before resting his hands on her shoulders. 'Have you had a good life, Sue?'

She nodded, 'I have. Harry has been an amazing father to me.'

'Come with me, Sue. Give me the opportunity to get to know you.'

She shook her head sadly. 'I can't, Doctor. You've crossed your own timeline and we can't change what's to come. You can remember coming here, seeing Sarah, even meeting Luke and thinking that he's yours. But you can't remember me. Our time isn't yet. If you remember me, things get all fouled up in the future.'

He pounced on one of her statements. 'We will have a time?'

'Oh yes, absolutely, but not yet and if you remember,' she paused, not wanting to think about the implications to her own past.

The Doctor finished the statement for her, 'I know, it will ruin everything that you've already gone through.'

'My past and everything that's happened would be for nothing.'

The Doctor smiled, 'Well, we can't have that, can we?'

Susan shook her head and was surprised when the Doctor quickly wrapped her in a large bear hug, resting his chin on the top of her head.

'This version of me never got to hold you as a child. I'm sorry I missed it. I could've taught you so much, Sue.'

Susan pulled back enough to look in his eyes and saw the raw emotion there. 'You did teach me so much, Doctor.' She couldn't help but have tears in her eyes as she looked at her true biological father for the first time. 'Even if you can't remember this moment, I will always treasure it because it gave me the opportunity to meet the version of you that Mum fell in love with. The one who loved her.'

'And I still do, if that means anything.'

'It does to me.' As they embraced as father and daughter for the first and last time, they each absorbed and memorised every second. Finally, Susan took a step back. 'It's time, Doctor. You need to forget me, forget this and move on.'

'I'm sorry I won't remember you the next time I see you, Sue.'

'It all eventually shakes out, over time. You'll just have to take my word on it for now.'

He nodded, 'Until we meet again, Susan.'

She took a couple of steps back towards the door without taking her eyes off of him. 'Mmm hmm,' she nodded. She headed towards the door, but then turned back at the last minute. 'Thank you,' she paused before adding, 'Dad.'

With that, she walked out the door and didn't turn back until the wheezing, groaning noise filled the room. She sighed deeply and let her head drop, not seeing Sarah enter the attic behind her.

Sarah walked over and wrapped an arm around Susan's shoulder as the TARDIS finished its dematerialisation. Sarah looked over and gave Susan's shoulders a squeeze as Susan brushed away a tear.

Susan rested her head on Sarah's shoulder. 'He's quite unforgettable, isn't he?'

Sarah laughed. 'Yes, you could certainly say that. That's one of the more outlandish versions of him I've ever known.' Quietly, she added, 'And I did love him.' Sarah sniffed to shake herself out of her own thoughts. 'Did you do what you needed to?'

Susan nodded, 'Yea. He'll go through with forgetting me like we discussed, but that should protect the timelines.'

'Good girl. I know that was tough.' Sarah wrapped her daughter in a warm hug.

Susan returned her mother's embrace. 'Oh yes. But the right thing to do isn't always easy. You taught me that, Mum.'

~!~!~!~


End file.
